Mathematics I / Rational and Irrational Numbers
Practice question · Numerical answer

Compute 2/3 + 3/4 and write the result in lowest terms. What is the numerator?

Hints
  1. Use a common denominator: multiply out as (ad + bc) over bd.
  2. Over 12 the two fractions become 8/12 and 9/12.
Show the answer

17

Why

2/3 + 3/4 = (2 x 4 + 3 x 3)/12 = 17/12, and gcd(17, 12) = 1 so it is already in lowest terms. The numerator is 17. Adding numerators and denominators separately, the classic error, would give 5/7, which is not even close.

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